The present disclosure relates to a motor vehicle having an internal combustion engine, an exhaust system, a turbine of a turbocharger arranged in the exhaust system and an exhaust gas aftertreatment device arranged in the exhaust system downstream of the turbine. Furthermore, the present disclosure relates to an operating method for operating the motor vehicle.
Vehicles may be equipped with various exhaust aftertreatment devices to reduce the release of exhaust emissions into the atmosphere. For example, three-way catalysts may reduce levels of various emissions including carbon monoxide and unburnt hydrocarbons while selective catalyst reduction (SCR) systems may be used to reduce levels of NOx. The exhaust catalyst may be effective in exhaust gas treatment above a catalyst light-off temperature.
DE 4139291 A1 shows a method for operating an internal combustion engine with exhaust gas turbocharging, in the case of which the exhaust gas turbine is subjected, at least at times, to additional fuel and/or combustion air supply with an elevated exhaust gas mass flow for achieving a detoxification of the exhaust gas and a rapid run-up of the exhaust gas turbine, the exhaust gas being catalytically ignited upstream of the turbine. A device for carrying out the method comprises an electrically heated catalytic converter, which is arranged parallel to a first exhaust gas line upstream of the exhaust gas turbine and which can be subjected to the exhaust gas flow at times by means of a shut-off valve.
CN 104500198 A discloses an electrically controlled exhaust system for a supercharged engine. The system comprises a compressor, a catalytic converter, an exhaust manifold and an exhaust bypass valve. A bypass valve control uses an electrically controlled actuator. The electrically controlled actuator is connected to an electrical control unit. A first branch-off pipe is in connection with a fourth branch-off pipe. A second branch-off pipe is in connection with a third branch-off pipe. Two paths of independent exhaust ports are formed at the outlet end of the exhaust manifold. The outlet end of the exhaust manifold is connected to an exhaust inlet of the compressor. The catalytic converter is connected to an exhaust gas outlet of the compressor in a closed coupling manner. This configuration is to realize a rapid discharge of exhaust gases and a shortened exhaust gas path.
However, the inventors herein have recognized potential issues with such systems. Operation of an exhaust turbine such as an electric turbine may increase the exhaust air fuel ratio (AFR), thereby causing reduction in exhaust NOx levels. However, during conditions when the temperature of the exhaust catalyst is lower than the light-off temperature, increase in exhaust AFR caused by electric turbine operation may further decrease exhaust temperature, thereby prolonging exhaust catalyst heating period. During the catalyst heating period (catalyst temperature below the light-off temperature), emissions quality may be adversely affected due to lower NOx conversion efficiency of the catalyst.
The present disclosure is based on the object of providing a motor vehicle and an operating method with which an improved exhaust gas aftertreatment can be achieved. In one example, the issues described above may be at least partly addressed by a system for a motor vehicle comprising: an internal combustion engine, a supply air system, an exhaust system, an exhaust gas aftertreatment device arranged in the exhaust system, a turbocharger including a turbine arranged in the exhaust system upstream of the exhaust gas aftertreatment device and a compressor arranged in the supply air system, an electric machine designed to drive the turbine or the compressor, and a heater designed to supply heat to the exhaust gas aftertreatment device, and a controller storing instructions in non-transitory memory executable to: supply energy to the electric machine to operate the turbocharger, and supply energy to the heater to heat the exhaust gas aftertreatment device, energy supplied to the heater based on the energy supplied to the electric machine. In this way, by concurrently providing power to the electric turbocharger and the catalyst heater, catalyst heating may be expedited, emissions quality may be maintained, and a desired boost pressure may be provided.
The motor vehicle according to the disclosure includes an internal combustion engine, a supply air system, an exhaust system, an exhaust gas aftertreatment device (also referred herein as exhaust catalyst) arranged in the exhaust system, and a turbine of a turbocharger arranged in the exhaust system upstream of the exhaust gas aftertreatment device or a compressor arranged in the supply air system comprises, according to the invention, both an electric machine which is designed in order to drive the turbine or the compressor, and a heater which is designed to supply heat to the exhaust gas aftertreatment device.
By way of this, a motor vehicle is provided, which by means of the electric machine can both create an E-boost and also heat up the exhaust gas aftertreatment device. Accordingly it is made possible to offset a cooling of the exhaust gas aftertreatment device by the use of the electric machine. The exhaust gas aftertreatment device thereby achieves a faster light-off and an improved performance.
In an advantageous configuration of the motor vehicle according to the invention, a further exhaust gas aftertreatment device is arranged in the exhaust system downstream of the exhaust gas aftertreatment device.
Thus, the exhaust gas aftertreatment device is arranged upstream of the further exhaust gas aftertreatment device and is the first of the two which are subjected to the flow of exhaust gas. The exhaust gas heated in the exhaust gas aftertreatment device by the heater can also heat up the further exhaust gas aftertreatment device. In addition, an improved pre-cleaning can take place in the exhaust gas aftertreatment device.
In a further advantageous configuration of the motor vehicle according to the invention, the heater is operated electrically.
Thus it is made possible to quickly activate the heater. In addition, electric energy, which was generated with the motor vehicle by means of recuperation, in particular brake recuperation, can thus be used. To this end, in a further configuration, the motor vehicle is designed for carrying out a recuperation, in particular a brake recuperation.
In a further advantageous configuration of the motor vehicle according to the disclosure, it comprises an exhaust gas recirculation system which is formed to conduct exhaust gas out of the exhaust system to a supply air system. Thus it is made possible to additionally perform an exhaust gas recirculation.
The operating method according to the disclosure for a motor vehicle having an internal combustion engine, a supply air system, an exhaust system, an exhaust gas aftertreatment device arranged in the exhaust system, and a turbine of a turbocharger arranged in the exhaust system upstream of the exhaust gas aftertreatment device or a compressor arranged in the supply air system, a heater for heating the exhaust gas aftertreatment device includes operating the heater in a heating mode in a first exercise for the exhaust gas aftertreatment device and operating the turbocharger in an E-boost mode, an electric machine is operated for driving the turbine or the compressor.
By way of the heating mode, the exhaust gas aftertreatment device is heated up so that the same can be brought into a temperature window (above light-off temperature) that is optimal for exhaust gas aftertreatment. In addition, a cooling of the exhaust gas aftertreatment device brought about by the E-boost operation is additionally offset by the heating mode. The power delivered to the heater for heating the exhaust gas aftertreatment device may be adjusted based on the operation of the turbocharger. As an example, if the turbocharger is operated at a higher speed to provide the desired boost and/or reduce NOx production, the exhaust air fuel ratio may increase (learner than stoichiometric) and the power supplied to the heater may be increased to compensate for the cooling effect of the increased exhaust air flow.
In an advantageous configuration of the operating method according to the invention, the first exercise is carried out in particular when in an E-boost check it was determined that a charge pressure undershoots a defined value, and it was determined in a temperature check that the exhaust gas aftertreatment device undershoots a defined temperature. The defined value may be based on an engine torque demand, and the defined temperature may be based on a light-off temperature of the exhaust gas aftertreatment device.
In an advantageous configuration of the operating method according to the invention, no heating operation is performed in a second exercise and the E-boost operation is carried out. Because of this, unnecessary heating of the exhaust gas aftertreatment device is avoided and the motor vehicle operated more efficiently.
In an advantageous configuration of the operating method according to the invention, the second exercise is carried out in particular when in the E-boost check it was determined that the charge pressure undershoots the defined value, and in the temperature check it was determined that the exhaust gas aftertreatment device does not undershoot the defined temperature.
In an advantageous configuration of the operating method according to the invention, no heating operation is carried out in a third exercise and no E-boost operation is carried out.
Because of this, unnecessary heating of the exhaust gas aftertreatment device and an unnecessary increase of the charge pressure are avoided and the motor vehicle is operated more efficiently.
In an advantageous configuration of the operating method according to the invention, the third exercise is carried out in particular when in the E-boost check it was determined that the charge pressure does not undershoot the defined value.
In a further advantageous configuration of the operating method according to the invention, an exhaust gas recirculation is additionally carried out in the first, second or third exercise. A cooling down of the exhaust gas aftertreatment device brought about by the exhaust gas recirculation can also be additionally offset.
In this way, by simultaneously operating the electric turbocharger and the electric heater coupled to the exhaust gas aftertreatment device, NOx production may be reduced while attainment of light-off of the exhaust gas aftertreatment device may be expedited. The technical effect of adjusting power delivered to the catalyst heater based on the power delivered to the electric motor coupled to the turbine or compressor of the turbocharger is that the cooling effect caused due to enleanment of the exhaust gas may be negated without over heating the catalyst, and battery power may be conserved. Overall, synergistic operation of the electric turbocharger and the catalyst heater may improve engine operation and emissions quality.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.